DESCRIPTION (Investigator's Abstract): Dr. Brown and co-investigators have been studying the capacity of various serum-free systems to support both short-term clonal and liquid culture of hemopoietic lineages. They have an extensive background in the serum-free and during phase I of this project they have developed a "unique kit" that supports proliferation and differentiation of erythroid and myeloid cells from human and murine marrow. The kit requires only the addition of cells in a one step assay. It consists of a pre-formed gel matrix containing medium, serum and growth factors. It appears to be equivalent to standard colony assays. They have also developed a serum-free medium which supported GM colony formation from human bone marrow cells in an equivalent fashion to serum containing media. They have developed data that the addition of interleukin-3 to serum-free systems can support liquid culture growth although studies on attempting to develop serum-free reagents for long- term human Dexter culture foundered on the inability to get stromal formation even with the addition of a variety of growth factors. Overall, the phase I studies have met all of their aims and have developed a solid base to proceed to their proposed phase II studies. In the Phase II studies, Dr. Brown hopes to optimize serum containing kits for CFR-GM, to develop and optimize serum containing kits for BFU-E, to replace albumin in the serum-free kit, to develop and optimize the serum-free kit for BFU-E, to optimize culture conditions with regard to these kits as to oxygen tension and cell concentration and to develop a liquid serum-free medium. During the course of these studies they will use standard clonal and liquid culture techniques, cell identification techniques and assess a variety of purified culture reagents.